The present invention relates generally to adaptors for connecting external medical devices to lead connector elements of medical leads extending percutaneously into a patient""s body, and more particularly to adaptors that shield the lead connector elements and connect external medical devices to heart wires for pacing, defibrillating and monitoring the heart and nerve and muscle stimulation wires for stimulating nerves and muscles.
Unipolar and bipolar surgically implanted temporary heart wires and temporary leads and nerve, organ, and muscle stimulation leads or wires are well known in the art, some examples of which may be found in the issued U.S. Patents listed in Table I below.
All patents listed in Table I are hereby incorporated by reference herein in their respective entireties. As those of ordinary skill in the art will appreciate readily upon reading the Summary of the Invention, Detailed Description of the Preferred Embodiments and Claims set forth below, at least some of the temporary leads and wires disclosed in the patents of Table I may be advantageously employed with the safety adaptor of the present invention.
Certain of the patents listed in Table I disclose surgically implanted temporary heart wires or leads for use with an external unipolar or bipolar cardiac pacemaker and/or monitor or pacing system analyzer (PSA) in a manner that is are well known in the medical field. As described further below, temporary heart wires are implanted in a patient""s body to extend between a heart chamber through a percutaneous incision to an external medical device and are removed after a time. Heart wires are sometimes alternatively referred to as temporary pacing leads but are distinguished from endocardial temporary pacing leads that are passed percutaneously through an incision into a vein and transvenously advanced into a heart chamber, typically employing a removable stiffening stylet, as disclosed in the above-referenced, commonly assigned ""861 and ""892 patents. Such endocardial temporary pacing leads are implanted and used for closed-chest temporary pacing and monitoring of a patient""s heart in a variety of single and dual chamber pacing modes. When their use is terminated, they are retracted through the transvenous route, and the incision is closed.
Unipolar heart wires, e.g., the Medtronic(copyright) Model 6491, Model 6492, Model 6494, and Model 6500 Temporary Pacing Leads, and bipolar heart wires, e.g., the Medtronic(copyright) Model 6495 Temporary Pacing Lead, are shown in the above-referenced, commonly assigned ""463, ""217 and ""328 patents. Such unipolar and bipolar heart wires are implanted in the course of a surgical procedure where the heart is surgically exposed, e.g., to provide post-surgical temporary pacing and monitoring, and are withdrawn through a percutaneous incision by applied traction when their use is to be terminated.
The elongated unipolar and bipolar heart wire bodies are constructed of a single conductor or two conductors, each conductor comprising a number of fine, stainless steel wires twisted together to form a single, flexible, multifilament wire. The major portion of each such conductor within the wire body is typically insulated with a polyethylene, polytetrafluoroethylene, silicone, nylon, or other suitable electrically non-conductive and bio-compatible materials to insulate the wires from one another (in bipolar versions) and from the environment. A short length of each such conductor at the distal end of the heart wire body is exposed to act as a pace/sense electrode when passed into the myocardium. The distal end of the most distal electrode is axially coupled to an elongated retention coil that in turn is coupled axially by a severable, non-conductive, filament to a fine, curved, surgical needle.
The fixation into the myocardium is accomplished with the heart exposed by using the curved needle to pierce the epicardium and to draw the pace/sense electrode(s) and retention coil through a portion of the myocardium without penetrating all the way through the myocardium and into a heart chamber or blood vessel. In this process, the needle is passed back out through the epicardium, and the filament coupling the needle with the fixation coil is severed after electrical testing is completed.
A tubular lead connector element is formed at the proximal end of the heart wire body and electrically connected to each insulated wire in an in-line configuration. A straight, Keith-type, cutting needle extends proximally from the proximal end of the most proximal lead connector element and is used to pierce the thoracic wall to extend the proximal portion of the heart wire body outside the body when the surgical incision accessing the heart is closed. Then, the Keith-type needle is typically clipped or broken off, and each heart wire connector element is coupled to an external medical device.
A similar nerve stimulation wire and procedure of implantation is disclosed in the above-referenced, commonly assigned, ""463, ""217 and ""328 patents.
The proximal connector elements of such temporary endocardial pacing leads and heart wires are typically coupled to terminals of external pacemaker pulse generators, e.g., the Medtronic(copyright) Model 5348 and 5388 single chamber or dual chamber pacemaker pulse generators. A direct connection may be made if the lead or wire connector elements are compatible with the external medical device connector terminals and if the lead or wire body is long enough. During surgery, it is necessary to locate the external medical device at a distance and out of the sterile surgical field that exceeds the exposed lead or wire body length. Similarly, it may be necessary to position the external medical device at a distance from a patient who is in post-operative recovery or is otherwise bed-ridden. In these cases, it is necessary to employ elongated cables with cable connector pins that are inserted into female connector terminals of the external medical devices and cable connectors that attach to the exposed heart wire or temporary pacing lead connector elements. Early cable connectors were simply formed as alligator clips that clipped over and made electrical connections with the exposed heart wire or temporary pacing lead connector elements. More recently, cable adaptors of the types disclosed in the above-referenced, commonly assigned, ""861, and ""892 patents provide enclosures for receiving the connector elements at the proximal ends of the endocardial temporary pacing leads while enabling insertion and removal of stiffening stylets. The above-referenced ""463, ""217, and ""328 adaptors facilitate breaking off the Keith-type needles and attach to the connector elements at the proximal ends of the heart wires or nerve wires.
Concerns relating to the safety of leaving any lead connector element exposed have been voiced by regulatory agencies over many years. It is dangerous to a patient, to conduct electrical current or static electricity through a lead into a patient""s body, particularly through a temporary pacing lead or heart wire attached to the heart. Connector regulations IEC 601-1 dictate that medical leads shall be constructed in such a way that no conductive part or surface of a connector element in the part of the medical lead remote from the patient can contact earth or possibly hazardous voltages.
What is needed is an adaptor that meets safety requirements for fully enclosing the lead or wire connector elements while providing simple and reliable electrical and mechanical connections to external medical devices.
The present invention has certain objects. That is, the present invention provides solutions to problems existing in the prior art. It is an object of the present invention to provide a safe and reliable adaptor for making an electrical connection between external medical device connector terminals and connector elements of a temporary medical lead. Such temporary medical leads include temporary pacing leads and heart wires and muscle, organ, and nerve stimulation leads and wires that extend percutaneously through the skin of a patient. It is a further object of the present invention to provide such a safety adaptor that fully encloses and isolates the medical lead connector elements from the environment and protects from inadvertently conducting an electrical current or charge into the patient""s body. Moreover, it is an object of the present invention to provide a simple mechanism for breaking away a beak-away needle attached to the proximal end of the temporary medical lead and then fully enclosing the lead connector elements.
The present invention has certain advantages. More particularly, the safety adaptor of the present invention: (a) is easy to use; (b) attaches to external pacemakers, defibrillators, monitoring equipment, nerve stimulators, and other external medical devices quickly, easily, securely, and reliably; (c) requires no use of an external, separate adapter or transition box or tool for separating or breaking the needle from the most proximal lead connector element; (d) has few parts; (e) is less expensive to manufacture; (f) helps reduce health care costs; (g) increases patient safety owing to shortened implantation procedure times, lowered risk of accidental electrical injury, and quicker connection to external medical device connector terminals; and (h) satisfies the IEC-1 connector safety regulations.
The safety adaptor of the present invention comprises a first member and a second member. The first member is attached with but movable with respect to the second member and has a elongated bore for receiving a lead proximal end segment including the lead connector elements. Temporary medical leads having a percutaneous penetration needle attached to the lead proximal end are so inserted such that the needle extends out of the elongated bore when the lead connector element(s) are seated within the first member. Preferably, a fulcrum is located at the point where the needle extends from the bore for detaching the break-away needle at a weakened zone connection with the proximal lead connector element, but the needle can be detached by other means. The second member has a breech for receiving the first member and proximal end segment after detachment of the break-away needle. The second member also has a set of breech connector terminals located in the breech for making electrical contact with the lead connector elements upon moving the first member into the breech that are connected via safety adaptor conductors to terminals of an external safety adaptor connector configured to connect with an external medical device connector or a cable.
In use, the break-away needle is advanced through a elongated bore of a first member of the safety adaptor such that the lead connector elements are seated within the elongated bore. Preferably, a weakened zone of the break-away needle is situated against a fulcrum of the first member, and the break-away needle is detached by bending its weakened zone over the fulcrum. The first member of the safety adaptor is moved into the breech of the second member of the safety adaptor such that electrical contact is made between lead connector element(s) and the respective breech connector terminal(s). The external safety adaptor connector terminals that are electrically connected with the breech connector terminals are then coupled with the external medical device connector terminals.
In one preferred embodiment, the safety adaptor comprises an elongated adaptor housing formed of an adaptor body and an adaptor arm that are hinged together at mutually hinged ends thereof and extend to adaptor body and adaptor body free ends, respectively. The hinged ends allow the adaptor arm to be moved from an open position wherein the free end of the adaptor arm is spaced from the adaptor body to a closed position wherein the adaptor arm is received in the breech of the adaptor body and locked therein. The adaptor arm and the breech that receives it in the closed position are shorter in length than the adaptor body, so that the free end of the adaptor arm is not exposed in the closed position. The adaptor arm includes an elongated bore extending from the hinged end to the free end for receiving the lead proximal end segment including the lead connector elements when the adaptor arm is either in the open or closed position. The adaptor body preferably incorporates at least first and second breech electrical terminals that are positioned along the length of the breech to bear against and make electrical contact with the lead connector element or elements inserted into the elongated bore and after the adaptor arm is moved to the closed position.
In a second preferred embodiment, the safety adaptor comprises an elongated adaptor housing formed of an adaptor body that extends between adaptor body first and second ends and has the breech formed therein for receiving an adaptor door. The adaptor door and adaptor body are hinged together at mutually hinged sides of the door and a door frame of the adaptor body. The hinged sides allow the adaptor door to be moved from an open position wherein the adaptor door is spaced from the adaptor body to a closed position wherein the adaptor door is closed against the door frame and the proximal end section of the lead in the elongated bore is received in the breech of the adaptor body and locked therein. The adaptor door and the breech that receives it in the closed position are shorter in length than the adaptor body, so that the second end of the adaptor door is not exposed in the closed position. The adaptor door includes an elongated bore extending from the first end to the second end for receiving the lead proximal end segment including the lead connector elements when the adaptor door is either in the open or closed position. As in the first embodiment, the adaptor body incorporates first and second breech electrical terminals that are positioned along the length of the breech to bear against and make electrical contact with the lead connector element or elements inserted into the elongated bore and after the adaptor door is moved to the closed position.
An exemplary electrical connector is incorporated into both preferred embodiments. The first and second breech electrical terminals are coupled with adaptor connector terminals of a shielded adaptor connector assembly that can be directly connected to a connector terminal assembly of the external medical device or through a separate cable to the connector terminal assembly of the external medical device. The shielded adaptor connector assembly can be formed within the free end of the adaptor body or at the end of a cable extending from the free end of the adaptor body.
A locking mechanism is preferably engaged upon completion of the insertion of the adaptor arm or door into the breech, and the lead connector element or elements bear against and make electrical contact with the adaptor connector terminals. The lead connector element or elements are fully enclosed within the adaptor such that it is not possible to make inadvertent or accidental electrical contact with the lead connector element or elements.
In use with a conventional break-away needle, the break-away needle and the proximal end segment are inserted through the elongated bore so that the break-away needle extends away from the free or second end of the adaptor arm or door. The weakened zone of the break-away needle is at a fulcrum of the free or second end when the lead connector elements are seated in the elongated bore. The break-away needle can be broken away by bending the weakened zone about the fulcrum elements at the free end or otherwise detached. Then, in the first embodiment, the free end of the adaptor arm and the lead connector elements within the elongated bore are pivoted about the hinge and back into the breech. In the second embodiment, the adaptor door is closed on the side hinge into the elongated breech of the adaptor body. Preferably, in both embodiments, a locking mechanism is engaged that prevents re-opening of the adaptor arm or the adaptor door.